It is hypothesized that extra pancreatic glucoreceptor cells play an important role in fuel homeostasis and that their function might be impaired in diabetes similar to the defect known to exist in pancreatic islet cells. We propose to perform basic biochemical investigations of two such glucoreceptor systems, the taste bud of the tongue and the hypothalamic satiety and feeding centers. The strategy is straightforward and draws its strength from proven principles of biochemical analysis, i.e., measurement of enzymes, intermediates and cofactor levels as indicators of molecular mechanisms coupled with rational physiological experimentation. Because of the microscopic nature of the structures, meticulous histological sampling techniques and highly sensitive chemical analytical methods will be applied. There is a virtual lack of sound biochemical information on these important biological systems. We are certain that the proposed studies will provide such information.